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Title: Millimetre-long transport of photogenerated carriers in topological insulators

Abstract

Excitons are spin integer particles that are predicted to condense into a coherent quantum state at sufficiently low temperature. Here by using photocurrent imaging we report experimental evidence of formation and efficient transport of non-equilibrium excitons in Bi 2-xSb xSe 3 nanoribbons. The photocurrent distributions are independent of electric field, indicating that photoexcited electrons and holes form excitons. Remarkably, these excitons can transport over hundreds of micrometers along the topological insulator (TI) nanoribbons before recombination at up to 40 K. The macroscopic transport distance, combined with short carrier lifetime obtained from transient photocurrent measurements, indicates an exciton diffusion coefficient at least 36 m 2 s -1, which corresponds to a mobility of 6 × 104 m 2 V -1 s -1 at 7 K and is four order of magnitude higher than the value reported for free carriers in TIs. The observation of highly dissipationless exciton transport implies the formation of superfluid-like exciton condensate at the surface of TIs.

Authors:
 [1];  [2];  [1];  [1];  [1];  [1];  [3];  [4];  [1];  [5]; ; ORCiD logo [1]; ORCiD logo [6]; ORCiD logo [1]
  1. Univ. of California, Davis, CA (United States)
  2. Shanghai Jiao Tong Univ. (China)
  3. Harvey Mudd College, Claremont, CA (United States)
  4. Arizona State Univ., Tempe, AZ (United States)
  5. Nanjing Univ. (China)
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division
OSTI Identifier:
1582362
Grant/Contract Number:  
AC02-05CH11231; DMR-1838532; DMR-1710737; DMR-1832728; PHY-1560482
Resource Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 10; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Electronic and spintronic devices; Topological insulators

Citation Formats

Hou, Yasen, Wang, Rui, Xiao, Rui, McClintock, Luke, Travaglini, Henry Clark, Francia, John Paulus, Fetsch, Harry, Erten, Onur, Savrasov, Sergey Y., Wang, Baigeng, Rossi, Antonio, Vishik, Inna, Rotenberg, Eli, and Yu, Dong. Millimetre-long transport of photogenerated carriers in topological insulators. United States: N. p., 2019. Web. doi:10.1038/s41467-019-13711-3.
Hou, Yasen, Wang, Rui, Xiao, Rui, McClintock, Luke, Travaglini, Henry Clark, Francia, John Paulus, Fetsch, Harry, Erten, Onur, Savrasov, Sergey Y., Wang, Baigeng, Rossi, Antonio, Vishik, Inna, Rotenberg, Eli, & Yu, Dong. Millimetre-long transport of photogenerated carriers in topological insulators. United States. doi:10.1038/s41467-019-13711-3.
Hou, Yasen, Wang, Rui, Xiao, Rui, McClintock, Luke, Travaglini, Henry Clark, Francia, John Paulus, Fetsch, Harry, Erten, Onur, Savrasov, Sergey Y., Wang, Baigeng, Rossi, Antonio, Vishik, Inna, Rotenberg, Eli, and Yu, Dong. Mon . "Millimetre-long transport of photogenerated carriers in topological insulators". United States. doi:10.1038/s41467-019-13711-3. https://www.osti.gov/servlets/purl/1582362.
@article{osti_1582362,
title = {Millimetre-long transport of photogenerated carriers in topological insulators},
author = {Hou, Yasen and Wang, Rui and Xiao, Rui and McClintock, Luke and Travaglini, Henry Clark and Francia, John Paulus and Fetsch, Harry and Erten, Onur and Savrasov, Sergey Y. and Wang, Baigeng and Rossi, Antonio and Vishik, Inna and Rotenberg, Eli and Yu, Dong},
abstractNote = {Excitons are spin integer particles that are predicted to condense into a coherent quantum state at sufficiently low temperature. Here by using photocurrent imaging we report experimental evidence of formation and efficient transport of non-equilibrium excitons in Bi2-xSbxSe3 nanoribbons. The photocurrent distributions are independent of electric field, indicating that photoexcited electrons and holes form excitons. Remarkably, these excitons can transport over hundreds of micrometers along the topological insulator (TI) nanoribbons before recombination at up to 40 K. The macroscopic transport distance, combined with short carrier lifetime obtained from transient photocurrent measurements, indicates an exciton diffusion coefficient at least 36 m2 s-1, which corresponds to a mobility of 6 × 104 m2 V-1 s-1 at 7 K and is four order of magnitude higher than the value reported for free carriers in TIs. The observation of highly dissipationless exciton transport implies the formation of superfluid-like exciton condensate at the surface of TIs.},
doi = {10.1038/s41467-019-13711-3},
journal = {Nature Communications},
number = 1,
volume = 10,
place = {United States},
year = {2019},
month = {12}
}

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